Rotative winged aircraft



May 8, 1945- H. s. CAMPBELL 2,375,465

ROTATIVE WINGED AIRCRAFT Filed June 19, 1941 2 Sheets-Sheet 1 INVENTCR.

May 8, v1945. H. s. CAMPBELL 2,375,465

ROTATIVE WINGED AIRCRAFT Filed June 19, 1941 2 Sheets-Sheet 2 ATTORNEY.S

Patented May 8, 1945 ROTATIVE WINGED AIRCRAFT nan-1| s. Campbell, BrynAthyn, Ps., signor to Autogiro Company of America, Philadelphia, Pa., acorporation of Delaware Application June 19, 1941, Serial No. 398,755

9 Claims.

This invention relates to rotative winged aircraft, and is particularlyconcerned with the initiation of rotation of the sustaining wings priorto making a. take-oli. Still further, the invention is of especialutility in an aircraft capable of direct or substantially verticaltake-01T.

For the purpose of effecting direct take-oil', an aircraft of the typehere involved is equipped with a variable pitch sustaining rotor whichis adapted to be driven while the machine is at rest on the ground to ahigh' number of revolutions, preferably in excess of normal flight R. P.M., the rotor blade pitch angle being maintained at a low value,desirably approximating zero pitch, so as to store a considerablequantity of kinetic energy. This energy may be released to efl'ectdirect takeoff by raising the blade pitch, this general type of take-offmaneuver being described more fully in copending application of Juan dela Cierva, Serial No. 738,349, filed August 3, 1934.

Certain features of the invention are particularly useful where thesustaining rotor of the aircraft (at or just before the take-oil) isdisconnected from thedriving engine and is actuated in flightautorotationally or aerodynamically, for which purpose the aircraft isequipped with a propulsive airscrew for inducing translational flight.

In accordance with the present invention, not only the sustaining rotor,but also the propulsive airscrew of such an aircraft, is capable ofvariation in pitch setting, and controls are provided by which duringacceleration of the rotor while on the ground in preparation fortake-oil, the propulsive airscrew pitch is reduced, thereby reducing thepower absorbed by the airscrew and making an equivalent increase ofpower Iavailable for transmission to the rotor for starting purposes.

The present invention contemplates the provision of a control systemensuring rapid airscrew pitch increase following the rotor accelerationperiod, in order to establish translational flight speed at a rapid rateand thereby avoid loss of altitude at the end of the direct take-ofimaneuver.

The invention also contemplates the employ-v ment of an adjustableairscrew pitch governor operating to stabilize the engine speed byincrease or decrease of the airscrew pitch with increase or decrease,respectively,.of the engine speed, and

or with the mechanism for connecting and disconnecting the rotor drive,or both.

It is also contemplated that the interrelation of controls provides forreduction of airscrew pitch only to that extent necessary to release thepower required to accelerate the rotor up to the take-off speed,provision being made for automatic increase of the airscrew pitch uponincrease of rotor blade pitch to eilect the take-oli. In this way aminimum of time is required for development of full airscrew thrust,which is of importance in eliminating loss of altitude at the end of thedirect take-01T maneuver.

The foregoing featuresare also of advantage and importance since theincrease of airscrew pitch at the time of making a take-olf ispreferably accompanied by disconnection of the rotor drive. In theabsence of such airscrew pitch increase, disconnection of the rotordrive would otherwise result in undesirable overspeeding of the engine.

How the foregoing and other objects and advantages are attained will beapparent from the following description, referring to the accompanyingdrawings, in which- Figure 1 is a diagrammatic view of certain elementsand devices of a rotative Winged aircraft arranged in accordance withthe present invention and provided with the control system hereincontemplated;

Figure 2 is a view similar trating a modification; and

Figure 3 is a detailed view of one part of the to Figure 1 but illus- I,control system of Figure 2.

' In Figure l, a rotor blade appears at I, it being understood that therotor would ordinarily incorporate a plurality of such blades pivotallyconnected with a common rotative hub, as by flapping and drag pivots, asWell as a. pitch change mounting, examples of which appear in Ray Patent2,216,163, issued October 1, 1940. The pitch angle of all blades may besimultaneously varied in the same sense by means of hydraulic cylinderand piston devices one of which appears at 5, connected with the bladethrough an arm '6, thisgeneral type of blade pitch control unit alsobeing disclosed in said Ray Patent.

The rotative hub is adapted to be driven from engine 1, as by driveshafting 8 and a discon nectible clutch which may appropriately beenclosed within housing 9. Free overrunning of the rotor with respect tothe drive may be assured by introduction of a freewheel clutch at .anyappropriate point in the drive system.

4gine may be varied.

Engine 1 also serves to drive thepropulsive airscrew I0, the blade pitchof this airscrew being controllable, for exampleqr/hyldraulic mechanismenclosed at I I, in a manner well understood in this art.

The invention employs an airscrew pitch governor I2 which, per se, maybeeof known type, the governor having a driving connection with theengine and being coupled with the pitch control mechanism I I by pipesI3 and I4. The governor is supplied with actuating fluid from a pump I5through a pipe I8. The pump I5, i. e., the source oi' iiuid pressure,may comprise the normal lubrication pump for the engine.

The pitch control and governor mechanismfor the airscrew provide forsubstantially constant engine speed by increase of airscrewpitch uponincrease of engine speed, and decrease of airscrew pitch upon decreaseof engine speed. In accordance with the invention, the equilibriumposition of the governor is adius able by means oi' a wheel I1 andcontrol connect lons hereinafter de scribed, so that the equilibriumspeed of the en-v Control of the pitch angle of the rotor blades is alsosecured through a hydraulic system, this system comprising a''pump I3,reservoir I9 and main control valve 20. Pressure is delivered from thepump to the control valve through pipe 2| and may be returned to thereservoir I9 through pipe 22, the reservoir also having a connection 23with the intake side of the pump, tc complete the circuit. It may herebe mentioned that a a clockwise direction, when viewed as in Figure 1,

to the vertical position, admits pressure fluid to pipe25 which isextended upwardly for connection with the cylinder and piston devices 5which are associated with the rotor blades, thereb;7 actuating arms' 6in a sense -to decrease the rotor blade pitch. Movement ci the blades 4to increased pitch position (upon relief of the fluid pressure) fordirect take-olf may be effected in a number of different ways, as by theemployment of a worm thread pitch mounting of the type shown in the Raypatent hereinbefore referred to, said.worm thread mounting being sooriented that the action of centrifugal force on the blades moves themKto increased pitch position upon relief of the fluid pressure.

Control handle 24 of valve 20 may also be further rotated in a clockwisedirection to the position indicated at 24a, in which uidpressure is notonly delivered to pipe 25 but further to pipe 26, which is extended to acylinder and piston device 21. The piston stem 28 'of this device iscoupled with an arm 29 for 'actuating the rotor drive clutch enclosedwithin the housing 9. `Introduction of uid into piston 21 engages therotor driving clutch and relief of pressure uid through pipe 26, valve20 and pipe 22 (as occurs withthe operating handle 24 in the positionshown in full lines) results in disconnection of the rotor clutch. g

The two iluid pressure control systems described above (one fortheairscrew pitch, andthe ner now to be described.

A pivoted control member or element 30 for the airscrew pitch governoris connected with .that governorby means of 'a pulley 3l andan endlesscable 32 passing4 not only over pulley 3I but over the governor pulleyI1. The angularly oifset lines a-a indicate a iiight range of adlowersthe equilibrium engine speed setting, a' stop 31 being employed to limitthe movement in this direction.

Member 30 may also be' angularly displaced considerably below the normalflight range af-a, for example to the position indicated in dotted linesat 30a, in which the member bears against stop 33. This lower positionof member 30 corresponds to a very high equilibrium engine speed (lowairscrew pitch) but will not result in racing For the purpose cieiecting movement of memv i ber 30 to position 30a, a fluid cylinder 39is provided, having a piston 40 projecting from the lower end thereof inposition to bear against the upper side of member 30. Fluid may beintroduced into cylinder 39 through connection 4I formed as a branch oipipe 23 hereinbefore ydescribed.

With the system of Figure 1, it is contemplated that a take-olf beefl'ect'ed in the following manner:

With the engine 1 idling, the control handle 24 of valve 20 is moved ina clockwise direction, which movement initially introduces pressure uid'to pitch control cylinder 5, thereby reducing the rotor blade pitch,and then introduces pressure fluid to pipe 26, and to branch 4I, therebyengaging the rotor driving clutch and moving the piston 40 downwardlyagainst arm 30 to carry the latter to the position indicated at 30a. Inthis position the pitch of the airscrew is substantially reduced fromthe normal ight range (the setting corresponding to a high equilibriumspeed of the engine), in view of which, in the absence of the drag ofthe rotor (now connected with the engine) the engine would operate atv aconsiderable overspeed. reduction of the airscrew pitch releases enginepower for transmission to the rotor, and the engine throttle is nowopened in order to increase engine speedand thus accelerate the rotor tothe R. P. M.desired for take-01T.

When the take-oir R. P. M. is' attained, the control handle 24 of valve20 may again be returned to the full line position, thereby releasingthe pressure in pipes 25, 26 and 4I. The eii'ect of this is todisconnect the rotor drive clutch and permit the rotor blade pitch toincrease, and still further to cause control member 30 to move upwardly(under the action of spring 35) to the position of adjustment in thenormal ilight range established by the setting of lever 33. Theconsequent increase in airscrew pitch absorbs the power of the enginewhich is no longer being transmitted to the rotor and thereby preventssubstantial overspeeding of the engine.

Eie'ctively, therefore,

The increase of rotor blade pitch converts the kinetic energy stored inthe rotor to lift and the machine commences the direct. take-ofimaneuver, during which the airscrew is rapidly developing its maximumthrust, so as to establish the translational flight speed necessary toavoid loss of altitude. It will be noted that the prevention ofoverspeeding of the engine is accomplished without the necessity ofadjusting the engine throttle.

In the modication of Figure 2, many of the parts are the same asdescribed above in connection with Figure 1. The valve 20a, however, isemployed only for control of rotor blade pitch by admitting andreleasing pressure fluid to and from pipe 25. The operating handle 24hof this valve has only two positions, and is biased by a spring 42 torelease position, as shown in full lines, in which pipe 25 is connectedwith the return line 22.

A pivoted latch 43 serves to retain lever 24h in the on position, asshown at 24o in dot and dash lines, in which pressure is delivered frompipe 2l to pipe 25, to reduce the rotor blade pitch, as before. Latch 43is coupled by link 44 with a pivoted lever 45 which is urged towardlatchengaged position by a spring 45. The free end of arm 45 is adaptedto be depressed by a trip member 441a carried by an arm 41 rigid withcontrol lever 48 which is pivoted at 49 and is coupled with the clutchactuating arm 23 byva push rod 50. Clutch operating lever 48 may beretained in clutch on or clutch oiT' positions 'by means of a latchcooperating with notches formed in the quadrant 5|. With thisarrangement, the rotor clutch is adapted to be engaged when the lever 48is moved to the on position. At' this time trip member 41a overlies thefree end of lever 45 (as indicated in dotted lines), and the latch 43engages control lever 24h in its on position. When lever 48 is moved tooff, the

trip 41a moves lever 45 downwardly therebydisengaging latch 43 andpermitting lever 24h to return to "release under the influence of spring42.

The control member 52 for adjustment of the airscrew pitch governor isconnected with a link 53 depending from arm 41 of the clutch controllever. As best seen in Figure 3, the connection of control 52 with link53 includes a slotted yoke 54 formed at the lower end of link 53, thisyoke being embraced by forks 55-5-5 projecting from control member 52. Apin 58 passes through these parts, including the slot in yoke 54, and arubber cushion 51 exerts pressure to cause forks 55-5'5 to frictionallyengage the yoke 54, thereby to maintain any adjusted setting of controlmember 52. A nut 58 may be employedto adjust the compression of therubber and thereby the frictional engagement of the parts.

The general operation of the control system of Figure 2 is similar tothat described above. In fact, if desired, this arrangement may beoperated, for the take-off, in the same manner as that speciiically setout with relation to Figure l. Thus, with the engine idling, the clutchcontrol lever 48 may be moved to the on position and the valve controlhandle 24h may also be moved to the "on position (as at 24e), the latterbeing retained by latch 43. The movement of clutch control lever 48 justdescribed also causes the control member 52 for the airscrew governor tomove downwardly, under the influence of upward movement of link 53,thereby causing a reduction in airscrew pitch.

The engine throttle may now be opened pro' 1 clutch control lever 48 mayb'e moved to the oil position, which disconnects the rotor drive clutchand trips lever 45 and latch 43, thereby permitting spring 42 to returnthe valve control handle 24h to release which eiects a raising of therotor blade pitch. At the same time this movement of the clutch controllever 48 moves the control member 52 for the airscrew governor upwardly,increasing the airscrew pitch, so as to absorb power which is no longerbeing transmitted to the rotor. Direct take-oil.' is occurring at thistime and the airscrew thrust rapidly picks up, so as to quicklyestablish translational flight speed.

The mechanism of Figure 2 is further capable of operation in a differentmanner,"according to which the control (52) for the airscrew governor isemployed as a jump-oil. control'by'f using it to regulate theacceleration of the rotor, as will now be described. However, it isfirst pointed out that, as indicated at b-b, the range of possiblemanual adjustment of member 52 when the clutch lever 48 is in oilposition is greater than that normally required for ilight adjustments,the latter range being indicated at c-c. When the clutch control lever48 is moved to the on position, the entire manually adjustable range isshifted downwardly, as indicated at bb, the segment of this total manualrange corresponding'to night adjustments also being shown at c-c'.

With this form of control, take-oil may be effected in the followingmanner:

With the engine idling, the rotor clutch is engaged and the rotor bladepitch reduced, and the control member 52 is set at a point, such as thatindicated at 1:, at which (with the rotor load on the engine) thegovernor operates to limit the engine and airscrew speed to an R. P. M.appreciably below the maximum engine speed limit, this setting beingmaintained during the initial portion of the .acceleration of the rotor.By way of example, the point :n may desirably be that position in which(with the rotor load on the engine) the governor imposes an equilibriumspeed at about 75% of maximum speed. It will be understood that withoutthe drag of the rotor on the engine, this setting would result insubstantial undesirable overspeeding of the engine, but this isprevented since the rotor drive clutch is at this time connected.

After acceleration of the rotor and engine up to a speed correspondingto point the pilot may then progressively lower control member 52 to apoint such as that indicated at y which, in eiect, reduces the airscrewpitch and thereby releases an increased portion of the power fordeliveryto the rotor. This causes further acceleration of the rotor,which can be controlled as desired, by the rate and the extent ofdownward movement of member 52. When the usual rotor tachometerindicates the attainment of the desired R. P, M. of the rotor, downwardmovement of member 52 is discontinued.

Upon the attainment of the desired rotor takeoff R. P. M., the clutchcontrol lever 48 is moved to the 01T position and the clutch is therebydisengaged, the rotor blade pitch increased and the control member 52swung upwardly so that the manually controllable range again occupiesits upper position. Since the point (for instance point y) to whichmember 52 was adjusted, normally lies within the flight adjustment rangeBy operating the mechanism in this'way, relaves -tively fine adjustmentsof the4 engine throttle 'e' notlrequired and, in addition, theairscrewfepitch is reduced only to that value necessaryizo-releasesumcient power to bring the rotor up to the desired take-oi!R. P. M. Therefore, return of the 10 airscrew pitch to the higher valueand re-development of the airscrew thrust consumes a minimum of time,and it is assured that only a. mini. mum of over-speeding of the enginewill occur during the transition from rotor-driven condition tofull-night condition. d Normally, it is preferable 'to operate at fullengine throttle during the latter part of the acccleration of the rotorpreceding take-off. 'This practice is advantageous since, uponde-clutching,

it isunnecessary to advancethe throttle to secure rapid increase ofairscrew thrust to the rmaximum obtainable. Utilizing maximumairscrewthrust during the take-oi! is of advantage since translational flightspeed is therebyquickly 25 established.

The arrangement of Figure 2 is capable of meeting varying operatingconditions, such as wind velocity, etc., for which purpose the pilot mayappropriately adjust the governor control member 62 throughout the widerange provided by the slot and pin interconnection between member 52 andlink 53. Y

I claim: v

1. In an aircraft having an engine and variable 35 pitch sustainingrotor and propulsive airscrew both adapted to be driven by the engine,an adjustable airscrew pitch governor providing a substantially constantequilibrium engine speed for a given engine throttle setting by increaseor de- 40 crease of airscrew pitch, means for varying the rotorpitch,and a common control system for adjusting the equilibrium engine speedestablished by the airscrew pitch governor and for actuating the meansfor varying the rotor pitch including operating connections providingfor simultaneous decrease of rotor blade pitch and increase of theequilibrium speed setting of the airscrew 'governor.

2. In an aircraft having an engine and variable 5 pitch sustaining rotorand propulsive airscrew both adapted to be driven by the engine, anadjustable airscrew pitch governo; providing a substantially constantequilibrium engine speed for a given engine throttlesetting by increaseor de- 5,

crease of airscrew pitch, means for varying the rotor pitch, adisconnectible rotor drive mechanism, and a common control systemincluding operating connections providing for conjoint connection of therotor drive mechanism with decrease of rotor blade pitch and increaseof1thel equilibrium speed setting 'of the airscrew governor, and forconjoint disconnection of the rotor drive mechanism with increase ofrotor blade pitch and decrease of the equilibrium speed setting of the05 airscrew governor. f

3. In an aircraft having an engine, a sustaining rotor, and a variablepitch propulsive airscrew, the rotor and airscrew both being adapted tobe driven by the engine, an adjustable airscrew pitch member foradjusting the equilibrium speed set- 75 v ting of said governor, saidmember being manually adjustable through a limited range for control odthe equilibrium setting in normal flight operation, a control device'for connecting Iand disconnecting the rotor drive, and meansDassociated with said member and said device providing automaticallyforadjustment ci said'member to an equili range upon actuation ofthecontrolv device to connect the rotor drive.

4. In an aircraft having an engine, a sustaining .rotor, and a variablepitch propulsive airscrew, l the rotor and airscrew both being adaptedto be driven by the engine, an adjustable airscrew pitch governorproviding a substantially constant equilibrium engine speed for a givenengine throttle `ber and said device for shifting said manual adjustmentrange in a sense such that with the rotor drive connected the manualadjustment range comprehends relatively high equilibrium speed settings.and that with the rotor drive disconnected the Amanual adjustment rangecomprehends relatively low equilibrium speed settings.

5. In an aircraft having an engine and variable lpitch sustaining rotorand propulsive airscrew both adapted to be driven bythe engine-anadjustable airscrew pitch governor providing a substantially constantequilibrium engine speed for a given engine throttle setting by increaseor decreaseof airscrew pitch, a disconnectible rotor drive mechanism, acontrol member for adjusting the equilibrium speed setting f saidgovernor, said member being manually adjustable through a limited rangefor control of the equilibrium setting in normal flight operation, acontrol device for connecting and disconnecting the rotor drive, meansfor varying the rotor blade pitch, and a control system associated withsaid member, said device and said means, and providingfor conjointreduction of rotor blade pitch, connection of the rotor drive andadjustment of said member to an equilibrium speed setting above. thenight range.

6. In an aircraft having an engine and variable pitch sustaining rotorand propulsive airscrew both adapted to be driven by the engine, anadjustable airscrew pitch governor providing a substantially constantequilibrium engine speed for 5 a given engine throttle setting byincrease or decrease of airscrew pitch, a disconnectible rotor drivemechanism, a control member for adjusting the equilibrium speed settingof said governor, said member being manually adjustable through alimited rangeI a control device for connecting and disconnecting therotor drive, means for varying the rotor blade pitch, and a control sys;tem associated with said member, said device and said means, andproviding for conjoint re-y duction of rotor blade pitch, connection ofthe rotor drive clutch and adjustment of said member to a position suchthat the range of manual adjustment comprehends relatively highequilibrium speed settings, the control system further providing forconjoint increase of rotor blade pitch, disconnection of the rotor driveclutch and adjustment of said member to a position such that the rangeof manual adjustment comprehends relatively low equilibrium speedsettings.

7. In an aircraft having an engine and variable brium speed settingabove the flight" pitch sustaining rotor and propulsive airscrew bothadapted to be driven by the engine, means for varying the rotor bladepitch, a control member for varying the airscrew pitch, said memberbeing manually adjustable over a limited range and being shiftable tomove said range between a position providing high airscrew pitchsettings and a position providing low airscrew pitch settings, andmechanism interrelating the operation of the means for varying the rotorblade pitch and of the said member, providing for shifting of saidmanual adjustment range to the position of high pitch settings uponincrease of rotor blade pitch.

8. In an aircraft having an engine and variable pitch sustaining rotorand propulsive airscrew both adapted to be driven by the engine, meansfor varying the rotor blade pitch, a disconnectilcnle drive for therotor, a control member for varying the airscrew pitch, said membr beingmanually adjustable over a limited range and being shiftable to movesaid range between a position providing high airscrew pitch settings anda position providing low airscrew pitch settings, and mechanisminterrelating the operation of the means for varying the rotor bladepitch, of the disconnectible rotor drive, and of said shiftable member,providing for conjoint connection of the rot-,or drive, decrease ofrotor blade pitch and shifting of said manual adjustment range to theposition of low airscrew pitch settings, and for conjoint disconnectionof the rotor drive, increase of the' rotor blade pitch and shifting ofsaid manual adjustment range to the position of high airscrew pitchsettings.

9. In an aircraft having an engine, a variable pitch sustaining rotorunit and a variable pitch airsorew unit, both units being adapted to bedriven by the engine, an adjustable pitch governor for one of said'unitsadapted to maintain a substantially constant equilibrium engine speed'for a given engine throttle setting by increase or decrease of the pitchof one of said units, means for Varying the pitch of the other of saidunits, and a common control'system for adjusting the equilibrium enginespeed established by said pitch governor of the one unit and foractuating the means for varying the pitch of the other unit, includingoperating connections providing for simultaneous increase of theequilibrium speed setting of the governor of said one unit and decreaseof the 'pitch of said other unit.

HARRIS S. CAMPBELL.

